1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly, to a semiconductor device having electrostatic discharge protection.
2. Description of the Prior Art
Electrical apparatuses usually include different devices that require different operating voltages, so a power conversion device is required to adjust (boost or buck) a voltage level to be stable at a preset voltage. In the prior art, the power conversion device utilizes a driving device to control a high-voltage switching device and a low-voltage switching device, and provides a required high voltage or low voltage by respectively turning on the high-voltage switching device or low-voltage switching device.
Since the high-voltage switching device and the low-voltage switching device operate in different voltage ranges, the driving device should be divided into a high-voltage region and a low-voltage region, and a high-voltage driving device disposed in the high-voltage region and a low-voltage driving device disposed in the low-voltage region also operate different voltages so as to have abilities to control the high-voltage switching device and the low-voltage switching device together. The high-voltage driving device is electrically connected to a high-voltage power and is driven by the high voltage generated from the high-voltage power. The driving device further includes a level shift device electrically connected between the high-voltage driving device and the low-voltage driving device, so that the high voltage can be reduced to the low voltage corresponding to the operating voltage range of the low-voltage driving device.
In the prior art, the high-voltage driving device and the low driving device are fabricated on a same substrate, and respectively disposed on different deep wells. The voltage range of the high-voltage driving device is designed to operate between 700 volts and 730 volts. However, when an ESD event occurs in the high-voltage driving device, static charges would be accumulated in the deep well of the high-voltage region, and the ESD voltage is easily larger than 1300 volts, so that a junction between the deep well of the high-voltage region and the substrate is easily broken down and damaged. Even the level shift device is also damaged.
As a result, to prevent the junction between the deep well of the high-voltage region and the substrate and the level shift device from being damaged by the ESD event is an important objective in this field.